Sorry, Cave diver here. Multiple reels/spools is very common.
Shorter cavern reel (easy to carry) brings me back to main line (buoy line) and keeps me within legal distance of flag.
Right, I understand the use of lines and jumps in cave diving, but I don't get what that has to do with towing a dive float on a shore dive. What's the reason for two lines? If you are going to carry a reel one way or the other, why not just carry that one that's attached to the float?
I still don't understand what you are describing, but I'm always happy to learn!